In industry, there is a strong necessity for process monitoring and in-line control for the minimization of time needed for production and quality control as well as for the reduction of production failures, losses and cost. The existing technology for process monitoring enables the in-situ determination of thickness and the optical properties mostly of inorganic coatings grown on stationary substrates by vacuum techniques such as evaporation as well as the ex-situ determination of properties of composite materials after the production and in small pieces. [1-13] Moreover, these methods include static measurements without the capability of monitoring in-line the quality of the grown coatings across the substrate and eventually of patterned films. Finally, none of the existing methods have been used or tested under conditions that characterize the industrial scale such as the dimensions of the substrates, the deposition time, the speed etc. [1-13]
The lack of monitoring and control systems in-line during the printing and treatment processes leads to limited production line performance since only the control of the final product takes place. This is very important since thin film processes are comprised of several stages, such as surface functionalization, printing of organic, hybrid and inorganic materials, that define the quality of the final product. In addition, thin films and multilayer properties are related to several physical parameters that have to be thoroughly controlled during the production.